Hi all from Aussie

[robertjusher]

Re: Hi all from Aussie

Talk with Darren from Total refractory, he has them and all the good info required. Prices are available, not sure about how cheap they are. They were the only people I spoke to about them.
ROb

[Aussie Pete]

Re: Hi all from Aussie

could anyone please point me in the right direction for stainless steel needles for my refractory dome,where to get and costing.
i've read somewhere to use 2.5%-5%...not sure how to work that out.
My oven is 39" wide, with a 19x11.5' door.

Should i really worry about them.???

[Aussie Pete]

Re: Hi all from Aussie

thanks David, i've found some verm. & perl at a hydroponics place, its about $35 for 100ltr for both perl & verm. Just about to start laying the bottom layer ready for the dome to be done
thanks for advice.

[david s]

Re: Hi all from Aussie

Like I said in a previous post I prefer to use the medium grade. I prefer to also do it in a couple of layers of about 35mm thick at a time, allowing a week or so(depending on weather) to dry.The grains tend to break up a bit if mixed for too long and the stuff tends to stick to the inside of the mixer so I find it better to mix in a barrow. Follow my recipe, including water quantity and you should get the right consistency. If you have any water at the bottom of the mix then you've added too much.

[Aussie Pete]

Re: Hi all from Aussie

evening all.....(well, morning).
With vermic. & perlite mix i was going to use on top of the blanket, what grade should it be, or doesn't it matter. Theres just different grades (coarse/medium), thought it was worth asking. I was going to do 50:50 verm & perl. mix on top.
How thick should this be layed...or should i do a few smaller thickness (to help with curing). Never done or seen before, so am in unchartered teritiory here.
When mixing, (will be done in cement mixer)i will add water last...what texture should it be like, should it stick together, how long should it mix for?
How long should this be left to dry/cure, before doing anymore.
thanks all

[Aussie Pete]

Re: Hi all from Aussie

oh yeh, heres a pic of progress so far...any thoughts welcomed.

[Aussie Pete]

Re: Hi all from Aussie

thanks guys, i have a cement mixer, is that the preferred way to mix, or do you guys mix by hand.
will hopefully be constructing the dome over the weekend, (how thick should i layer it?, i was thinking about 2-3"), then i will let that dry out over a few weeks and possibly light a few small fires in it.
Am getting a bit of rain around here lately, i have a portable gazebo over the construction area for now, but how do you guys keep the rain out of your ovens, surely the rain would get in the door somehow. Even on heavy rain days, the rain would surely get in the flue & down onto the floor bricks wouldn't it?

[Johnny the oven man]

Re: Hi all from Aussie

Pete, when you do the mix, add all your dry ingredients together, mix thoroughly and THEN add water.

[david s]

Re: Hi all from Aussie

You can use one or the other, I just found that it holds together better if you have a mix of the two, it makes it easier to apply. The alternative is to add more cement, but that reduces the insulating capacity.

[Aussie Pete]

Re: Hi all from Aussie

excellent!!...thanks dave, thanks david..
1 last question, then you guys can go to bed...

is it imperitive that both verm & perl are used, can i just use 1 or the other, whats the chemistry with using both....

nite nite

[david s]

Re: Hi all from Aussie

Perlite and vermiculite are both silica based minerals that fizz up like popcorn at around 600 C perlite is a better insulator when dry, although when cement is added there is little difference in their insulating capacity. The perlite contains more fine dust I've found so needs a bit more care to handle as it is irritating to breathe. Ask for a medium grade. The finer grades will require more water in the mix. The coarse stuff doesn't stick together so well. This is my experience, it may well depend on where your supply comes from, there is quite a difference in the characteristics of these materials depending on source.

[cobblerdave]

Re: Hi all from Aussie

thanks Johnny & dave, i think i will go the mix you mentioned dave, seems ok to me. I am sure there are so many different mix's people have used, but i'll just go with what has worked i suppose. Also 50/50 verm. you mentioned, is that verm. & perl. with water?
What type of shops sell verm & perl, is it nursery type places or bunnings.
How much would i need for approx. a 36" oven?
I think i am going to have some refractory mortar left over after completing the dome, could i use that with some verm mixed into it? If i was going to do that, which would be better to use verm or perl?
Come to think of it....whats the difference?

Try Oasis hydroponics in Capalaba 100 ltr for approx $35 of different grades and sizes

Regards Dave

[david s]

Re: Hi all from Aussie

. Also 50/50 verm. you mentioned, is that verm. & perl. with water?
What type of shops sell verm & perl, is it nursery type places or bunnings.

Yes, 5:5:1:3 vermiculite, perlite,cement,water. Get it from nurseries, hydroponics suppliers or someone like Elders.
At a guess you'll need two 100 litre bags of each. They are about $35/bag
You could add the mortar to it but it will reduce its insulating capacity.

[Aussie Pete]

Re: Hi all from Aussie

thanks Johnny & dave, i think i will go the mix you mentioned dave, seems ok to me. I am sure there are so many different mix's people have used, but i'll just go with what has worked i suppose. Also 50/50 verm. you mentioned, is that verm. & perl. with water?
What type of shops sell verm & perl, is it nursery type places or bunnings.
How much would i need for approx. a 36" oven?
I think i am going to have some refractory mortar left over after completing the dome, could i use that with some verm mixed into it? If i was going to do that, which would be better to use verm or perl?
Come to think of it....whats the difference?

[david s]

Re: Hi all from Aussie

I use 5:5:1:3 vermiculite, perlite,GP Portland cement, water. Using one hand on the outside and one hand making a horizontal ledge at the top. Apply one handful at a time and starting at the bottom of the dome work all the way around in a layer about 35mm thick. the water pretty much stays in this layer and you won't get too much being sucked into the blanket. You will think "this isn't going to work", but it does and it sets up hard enough so that you can render/stucco over it. The 50/50 vermiculite, perlite works way better than either of them alone for some reason. Try mixing up one batch of 10 litres and applying it then let it set for a day or two and see what you think. The more cement you add the less effective it is as an insulator. I dry mix the aggregate and cement then add the water. Leave the layer for a week to dry out before curing ,then rendering.